Electrical switching devices, for example low-voltage circuit-breakers in the form of so-called compact switches—known as MCCBs (Molded Case Circuit Breaker)—or in the form of so called open circuit breakers—known as ACBs (Air Circuit Breaker) are used to interrupt single-phase or multiple-phase current paths of a main circuit. The current paths are interrupted in such cases by mechanical opening of single-break or double-break switching contacts. In such cases the switching contacts must be arranged electrically insulated.
This insulation must be provided both from the installation environment and also—for multi-phase electrical switching devices—between the individual phases of the main circuit. In order to achieve this the parts of the electrical switching device which are assigned to such a phase of the main circuit and form a switching pole are each mounted in a separate switching compartment which is delimited by an insulating surround. These insulating surrounds—especially consisting of plastics—which also include a full range of rigid housing arrangements differing in their external appearance, at the same time prevent the unimpeded propagation of gas and particle releases arising during switching processes.
Thus these insulated surrounds typically essentially reside in a known housing arrangement in a lower housing part divided into chambers according to the number of switching poles and a suitable upper housing part, which are generally joined to each other by screw connections.
With the use of rotary double contacts (contact bridges) another housing concept, known as “cassette construction” has become established, in which a switchable, double-breakable contact bridge, together with two arc extinction chambers and possibly other components needed for each switching pole (slot motor, etc.) are arranged in an almost closed switching pole housing generally consisting of at least two half shells (individual pole cassettes). These prefabricated individual pole cassettes must now be combined into switching devices with the required number of poles in each case. In such cases the modularity and thus for example also the exchangeability of individual of the switching poles is to be retained.
In addition this combination of the switching pole housing (individual pole cassettes) is to be undertaken while guaranteeing maximum stability, since strong forces occur there between the individual switching poles of electrical switching devices during switching actions (especially when switching off in the power limit range of the switching devices) as a result of the magnetic field surrounding the individual phases of the current path, the necessity arises to restrict as far as possible a relative movement of the individual pole cassettes in relation to one another as a result of the forces acting on them.
A multipole electrical switching device in the form of a low-voltage circuit breaker is known from the German translation DE 602 11 028 T2 of the European patent EP 1 464 063 B1 for example, in which, in an outer housing referred to as a cover, a number of separate switching pole housings are accommodated between the sidewalls of the outer housing. In this known multipole electrical switching device each of the switching pole housings forms an insulating surrounding of the switching space for accommodating an individual switching pole of the electrical switching device. To provide a secure connection of the switching pole housing in respect of the forces acting during switching and in this case to avoid complicated joining operations, the switching pole housings, which are each formed from two half shells, have insulating channels which, in relation to dividing joints separating the half shells, extend transversely through the switching pole housing. The separate switching pole housings of the switching poles are connected in this case by spanning and transverse connection elements which extend right through the insulating channels.
Starting from a multipole electrical switching device with an outer housing, in which at least two separate switching pole housings are accommodated, which each form an insulated enclosure of a switching compartment to accommodate an individual switching pole, in which the at least two separate switching pole housings on the walls facing towards each other each feature at least one mounting which form a mounting pair, whereby for mechanical connection of the at least two separate switching pole housings the mounting pair is assigned a connection means that engages into the two mountings forming the mounting pair (German translation DE 602 11 028 T2 of the European patent EP 1 464 063 B1), the underlying object of the invention is also to create a secure connection of the switching pole housings in respect of the forces acting on them during switching and in doing so to avoid complicated joining operations.